The relatives of a teenage suspect in a baby's shooting death have been arrested on charges of lying to police.

The aunt and the mother of 17-year-old De'Marquise Elkins were taken into custody on Tuesday after giving police new information that led to a pond where police found a handgun.

The gun is now being tested to determine if it was used in the Thursday killing of 13-month-old Antonio Santiago.

Antonio's mother, Sherry West, told police that two boys approached her and demanded money as she walked with her baby in his buggy in Brunswick, Georgia.

She said she told the muggers she had no money and tried to shield her boy, but one of them pushed her aside and shot the baby.

Image:De'Marquise Elkins and Dominique Lang are jointly accused

"I put my arms over my baby and he shoves me, and then he shot my baby right in the head," Ms West said.

She was shot in the leg and said her ear had been grazed by a bullet.

Elkins and 15-year-old Dominique Lang were arrested later that day and have been charged with murder as adults.

Tuesday's arrest of Karimah Elkins, the suspect's mother, and Katrina Elkins, his aunt, came days after Katrina Elkins told reporters her nephew could not have taken part in the murder because he was having breakfast at her house at the time of the killing.

Police said before the arrests that they had been looking at school attendance records as part of their investigation.

Ms West has said in interviews that she wants the death penalty for her baby's killer.